This invention relates to an electromagnetic induction apparatus with a sound suppressing arrangement and, more particularly, to a sound suppressing arrangement for reducing the noise generated by an electromagnetic induction apparatus such as an electrical transformer.
FIG. 1 is a sectional view showing the conventional electromagnetic induction apparatus of this kind, in which reference numeral 1 designates an electrical coil assembly of an electromagnetic induction apparatus, 2 is an electrically insulating oil, 3 is a tank main body in which the coil assembly 1 is housed together with the insulating oil 2, 31 is a tank side plate constituting one portion of the tank main body 3, 32 is a tank bottom plate constituting one portion of the tank main body 3, 4 are reinforcing members for the tank side plate 31, 5 are sound shield members mounted to the reinforcing members 4, 6 are heavy objects attached to the sound shield members 5, 7 are reinforcing members for the tank bottom plate 32, 8 are electrical bushings connected to the coil assembly 1 mounted in the tank main body 3, 9 is a floor surface on which the electromagnetic induction apparatus is installed and 10 are spaces defined between the reinforcing members 7, the tank bottom plate 32 and the floor surface 9.
In this conventional design, the coil assembly 1 of the electromagnetic induction apparatus vibrates in all vertical and horizontal directions due to an electromagnetic force during normal operational conditions of the induction apparatus. This vibration is transmitted through the electrical insulating oil 2 to vibrate the tank main body 3, causing a noise.
Therefore, in order to reduce the noise generated by the vibration of the tank side plates 31, the sound absorbing member 5 is mounted to the reinforcing member 4 attached to the side plates 31 of the tank main body 3, and a heavy object 6 is additionally attached to the sound absorbing member 5 to improve the sound absorbing function of the sound absorbing member 5.
Since the conventional electromagnetic induction apparatus with a sound suppressing arrangement is designed as above-described, while the noise generated due to the vibration of the tank side plate 3 can be effectively reduced by the sound absorbing members 5 attached to the tank side plates 3, the noise generated by the tank bottom plate 32 and radiated from the space 10 defined between the reinforcing members 7, the bottom plate 32 and the floor surface 9 cannot be effectively reduced. Therefore, it has been necessary to provide a large scale sound insulating arrangement such as a sound shield wall or the like around the induction apparatus in order to effectively reduce the noise of the conventional electromagnetic induction apparatus.